Dual Fuel Engine Combustion Control via Cylinder Pressure Feedback
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Solution Overview
Problem
Dual fuel gas/diesel engines face challenges in controlling combustion phasing and noise due to sensitivity to diesel injection timing and chemical reaction kinetics, which are affected by pressure, temperature, and cylinder charge composition, leading to inefficiencies and increased CO2 emissions.
Innovation Solution
Implementing a feedback control system based on measured cylinder pressure to adjust the start and duration of diesel injection, minimizing diesel quantity and maximum pressure rise rate, thereby controlling combustion phasing and noise, using a PI-controller with input transformation to stabilize the system and ensure efficient combustion with reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If diesel injection timing is adjusted to control combustion phasing, then combustion efficiency is improved, but combustion noise and pressure rise rate increase
Solution Approach 1:
The patent implements a feedback control system that measures cylinder pressure and uses this information to adjust diesel injection timing in real-time. The controller monitors the actual combustion phasing and pressure rise rate, comparing them against target values, and dynamically modifies injection timing to maintain optimal combustion efficiency while suppressing excessive noise and pressure fluctuations.
Solution Approach 2:
The system dynamically adjusts diesel injection timing based on real-time combustion conditions rather than using fixed timing. The injection timing is continuously modified cycle-to-cycle based on measured cylinder pressure, allowing the system to adapt to varying operating conditions and maintain optimal balance between efficiency and noise control.
2Object-generated harmful factors
If diesel quantity is reduced to lower emissions, then CO2 emissions decrease, but combustion stability deteriorates
Solution Approach 1:
The feedback control system continuously monitors cylinder pressure to detect combustion quality and stability. When diesel quantity is reduced, the system uses pressure feedback to detect any deterioration in combustion stability and automatically adjusts injection timing to compensate, maintaining reliable combustion even with reduced diesel quantities and thereby lowering CO2 emissions.
Solution Approach 2:
The system changes combustion parameters dynamically by adjusting injection timing based on measured pressure conditions. This allows the engine to operate with optimized diesel quantities for emission reduction while compensating for reduced combustion stability through real-time timing adjustments, maintaining reliable operation across varying conditions.
3Stability of the object's composition
If feedback control is implemented to stabilize combustion, then combustion phasing control improves, but system complexity increases
Solution Approach 1:
The patent implements feedback control using cylinder pressure measurement as the feedback signal. This approach provides direct information about combustion phasing and quality, enabling effective control without requiring complex sensors or measurement systems. The simplicity of using readily available pressure data helps minimize system complexity while achieving stable combustion phasing control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The feedback control system effectively stabilizes combustion phasing and noise, reducing diesel consumption and maintaining efficient engine operation, achieving diesel-like efficiencies without the need for a lean de-NOX system and minimizing CO2 emissions.
Implementation Method 1
Feedback control based on the measured cylinder pressure has been applied successfully to conventional diesel engines
Implementation Method 2
The start of combustion depends on the start of injection of the diesel and on the ignition delay of the diesel. The latter is mainly dependant on the chemical reaction kinetics of the diesel fuel.
Implementation Method 3
The premixed air-gas mixture is then ignited with a small amount of directly injected diesel
Data Source
AI summary
Feedback control of combustion in a gas diesel dual-fuel engine (20), based on the measured cylinder pressure, has been invented. The center of combustion and pressure rise rate is controlled by manipulating the start of diesel injection and duration of diesel injection. Measurements of transient engine operation show, that the proposed controller is able to control the center of combustion and the maximum pressure rise rate. The influence of changing intake manifold pressure, changing exhaust gas recirculation rate and changing air-fuel ratio can be compensated by the controller (10). Steady state measurements show that the gas diesel dual fuel engine reaches efficiencies around 40% with stoichiometric air-fuel ratio and diesel ratios below 5%. The results have been obtained on a slightly modified production type common-rail diesel engine with four cylinders and a displacement volume of 2 liters.